This invention relates to a method for manufacturing an absorbent article with a predetermined pattern arranged at a predetermined position thereof
Absorbent articles such as disposable diapers are occasionally provided at a predetermined position thereof with a predetermined pattern for the purpose of easy front and rear discrimination. For example, shorts-type diapers for use of children which are manufactured through a cross-flow processing method are occasionally provided at a rear body part thereof with a pattern continuously formed in a widthwise direction or at a central area of a rear body part thereof with a one-point pattern for the purpose of easy front and rear discrimination. Such a pattern is formed by applying a coloring to an elastic member at a waist part, by marking a waist part, or by adhering a colored string to a waist part. In general, front and rear are discriminated by applying a printing pattern to a material of shorts-type diapers and such a pattern has been beloved by mothers and children. As a pattern for diapers for use of children, an animal picture, a vehicle picture, a letter, a food and the like are favorably accepted.
As a technique for continuously producing disposable diapers, there is one which is disclosed in U.S. Pat. No. 5,045,135. As a technique for applying a pattern to a diaper, there is also one which is disclosed in Japanese Pat. No. 2616999.
Conventionally, there has been known a technique, as a technique for applying a predetermined pattern to a predetermined position of a diaper, in which an in-line printing machine is arranged at a midway of a manufacturing line, a pattern is printed on a forming material of an absorbent article such as a leak-preventive sheet in line, and the forming material with a pattern printed thereon is arranged at a predetermined position of the absorbent article. However, such a method is liable to contaminate the manufacturing line. Moreover, in the case where there are a plurality of manufacturing lines, a printing machine is necessary for each manufacturing line and therefore, the cost for the pattern printing is increased. In addition, in the case where a multicolor is to be printed, that number of plates and printing facilities which corresponds to the number of colors become necessary. Thus, many days are required to employ such facilities and in addition, such printing facilities are expensive. In the case where printing is to be changed, not only much expense is required in accordance with the number of lines and plates but also many days are required for employing that number of printing facilities, etc. Moreover, in the case where a solvent-based printing ink is used, ambient air is deteriorated. In the case where a drying process is employed, the line length becomes extremely long. Although there is a printing apparatus using an ink jet, the printing quality is degraded when printing is made at a high speed and positional alignment is extremely difficult in multicolor printing.
In general, a sheet such as film, nonwoven fabric, paper, elastomer and the like onto which a printing is preliminarily applied at constant pitches is difficult to be taken up at a uniform tension from a winding outer part to a winding tail part at the time of taking up a raw sheet into a roll form. Due to non-uniform tension, printing pitch varies when the sheet is fed out from the taken-up roll. Accordingly, when attempt is made to apply a pattern onto the absorbent article using such a sheet, variation of pitch at the time of feeding out the sheet must be corrected in order to make the printing position of the sheet in alignment with the predetermined position of the absorbent article. That is to say, since the printing pitch of the sheet fed out is non-uniform, the feeding amount of the sheet must be changed by increasing or decreasing the speed for feeding out the sheet. However, if the sheet should be overly fed out at that time, tension of the sheet would become zero and sagging and wrinkling (vertical, horizontal and oblique) would occur to the sheet, thereby causing the sheet to travel in a zigzag course. Making the sheet tension zero resulted in degraded product and trouble of a manufacturing line. That is to say, it was conventionally extremely difficult to apply a pattern to a predetermined position of the absorbent article using a sheet with a pattern preliminarily printed thereon.
It is, therefore, an object of the present invention to provide a method for manufacturing an absorbent article, in which an absorbent article with a predetermined pattern arranged at a predetermined position can be manufactured efficiently, economically and in a stable manner without producing a degraded product.
The present invention has achieved the above object by providing a method for manufacturing an absorbent article comprising the steps of continuously feeding out a long, extensible, continuous member from a predetermined position and conveying, cutting the continuous member into lengths each equivalent to a length of one sheet of the absorbent article at a predetermined position in a conveying path, and fixedly arranging the cut continuous member at a predetermined position of the absorbent article, wherein a predetermined pattern is preliminarily printed on the continuous member at a printing pitch shorter than the cutting length of the continuous member, and the speed for feeding out the continuous member is controlled such that the predetermined pattern is located at a predetermined part of the cut continuous member, thereby obtaining the absorbent article in which the predetermined pattern is arranged at a predetermined position. The expression xe2x80x9cextensiblexe2x80x9d used herein refers to extension in the longitudinal direction, and the expression xe2x80x9ccut continuous memberxe2x80x9d refers to the individual members produced as a result of cutting the continuous member. More preferably, the continuous member is elastically extensible.
Moreover, the present invention provides a long, continuous member preferably used in the above-mentioned method for manufacturing an absorbent article, i.e., which is joined with other members and cut into product lengths each equivalent to a length of one sheet of the absorbent article, together with the other sheet, so as to be used as a part of an absorbent article, wherein patterns are printed on the continuous member in a longitudinal direction thereof at a pitch shorter than the product length, and the printing pitch of the patterns can be made coincident with the product length by extending the continuous member in the longitudinal direction in any step up to the joint with the other members